Valve and fluid control apparatus

ABSTRACT

A valve includes a lower valve housing, a diaphragm, and an upper valve housing. A top surface of a piezoelectric pump is bonded to a bottom surface of the lower valve housing. A circular hole portion is provided in a central portion of a region of the diaphragm that opposes a projecting portion of the lower valve housing. The diaphragm is bonded to the upper valve housing and the lower valve housing, and a divided interior of a valve housing configures a first lower valve chamber, a second lower valve chamber, a first upper valve chamber, and a second upper valve chamber. A groove is located in a wall portion of the upper valve housing that opposes the diaphragm in the first upper valve chamber.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to valves that prevent backflow of afluid, and to fluid control apparatuses provided with such valves.

2. Description of the Related Art

Japanese Unexamined Patent Application Publication No. 2002-106469discloses a diaphragm pump provided with a valve.

FIG. 14 is an exploded perspective view illustrating a diaphragm pump 90according to Japanese Unexamined Patent Application Publication No.2002-106469. FIG. 15 is a cross-sectional view illustrating the primarycomponents of the diaphragm pump 90 shown in FIG. 14.

The diaphragm pump 90 is configured of a housing 900 provided with anexhaust channel 901 and an intake channel 902, and a diaphragm 910 forforming a pump chamber with the housing 900. The housing 900 isconfigured of an upper housing portion 930, a lower housing portion 940,and a diaphragm (film) 920.

An intake channel groove portion 942 through which air is sucked intothe pump chamber from outside of the housing 900, an exhaust channelgroove portion 941 through which air is exhausted from the pump chamberto the outside of the housing 900, an approximately cylindrical recessportion 945, an approximately cylindrical recess portion 946, acylindrical platform 947 located in the center of the recess portion946, a projecting portion 944, and a projecting portion 943 are providedin the lower housing portion 940.

The exhaust channel 901, the intake channel 902, a recess portion 935that opposes the recess portion 945, a recess portion 936 that opposesthe recess portion 946, a cylindrical platform 937 located in the centerof the recess portion 935, a projecting portion 934 that is bonded tothe projecting portion 944, and a projecting portion 933 that is bondedto the projecting portion 943 are provided in the upper housing portion930. The diaphragm 910 is bonded, using an adhesive, to an outer edgeportion in an upper surface of the upper housing portion 930, the outeredge portion being located further toward an outer side portion than theexhaust channel 901 and the intake channel 902.

A hole portion 921A that faces the platform 947 and a hole portion 921Bthat faces the platform 937 are provided in the diaphragm 920.

The upper housing portion 930 and the lower housing portion 940 arebonded to each other, with the diaphragm 920 located therebetween, usingan adhesive. Accordingly, the diaphragm 920 is sandwiched between theupper housing portion 930 and the lower housing portion 940.

As shown in FIG. 15, an intake valve is configured by the recessportions 936 and 946, the platform 947, and the periphery of the holeportion 921A and the hole portion 921A in the diaphragm 920. The intakevalve allows a fluid to flow from the intake channel groove portion 942side toward the diaphragm 910 side but prevents the fluid from flowingfrom the diaphragm 910 side toward the intake channel groove portion 942side.

Meanwhile, an exhaust valve is configured by the recess portions 935 and945, the platform 937, and the periphery of the hole portion 921B andthe hole portion 921B in the diaphragm 920. The exhaust valve allows thefluid to flow from the diaphragm 910 side toward the exhaust channelgroove portion 941 side but prevents the fluid from flowing from theexhaust channel groove portion 941 side toward the diaphragm 910 side.

The diaphragm pump 90 configured as described above is operated bycausing the diaphragm 910 to bend.

When the diaphragm pump 90 is driven, the periphery of the hole portion921A in the diaphragm 920 separates from the platform 947, and theperiphery of the hole portion 921B in the diaphragm 920 separates fromthe platform 937. As a result, the exhaust valve and intake valve eachopen, and air flows in from the intake channel groove portion 942 and isexhausted from the exhaust channel groove portion 941.

However, in the diaphragm pump 90, there are cases, during driving,where the pressure on the diaphragm 910 side of the diaphragm 920increases suddenly. In such a case, in the exhaust valve, the peripheryof the hole portion 921B in the diaphragm 920 will separate by asignificant amount from the platform 937 and make contact with therecess portion 945 in the lower housing portion 940. In other words, thehole portion 921B is covered by the lower housing portion 940 and theexhaust valve is blocked.

Accordingly, with the diaphragm pump 90, there is a problem in that thediaphragm 920 in the exhaust valve deforms greatly and the transport offluid will stop in the case where the pressure acting on the diaphragm910 side of the diaphragm 920 is much higher.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a valve, whichblocks the flow of a fluid from one main surface side of a diaphragm toanother main surface side of the diaphragm, that prevents the transportof fluid from stopping even in the case where pressure on the other mainsurface side of the diaphragm has become extremely high, as well as afluid control apparatus provided with such a valve.

A valve according to a preferred embodiment of the present inventionincludes a valve housing provided with a first opening portion and asecond opening portion, and a diaphragm, provided with a hole portion,that divides the interior of the valve housing so as to configure, inthe valve housing, a first valve chamber configured to communicate withthe first opening portion and a second valve chamber configured tocommunicate with the second opening portion, the hole portion is coveredby a periphery of the hole portion in the diaphragm making contact withthe valve housing in the first valve chamber, and a flow channelformation portion is provided in at least a portion of a wall portion ofthe valve housing that opposes the diaphragm in the second valvechamber, the flow channel formation portion defining a flow channelconnecting the first valve chamber and the second valve chamber when theperiphery of the hole portion in the diaphragm makes contact with thewall portion.

In this configuration, the first opening portion preferably is connectedto a pump, for example. The second opening portion preferably isconnected to a fluid holding portion such as a cuff for blood pressuremeasurement, for example.

Even in such a configuration, when the second valve chamber faces onemain surface of the diaphragm and the first valve chamber faces anothermain surface of the diaphragm, there are cases where a pressure in thefirst valve chamber becomes much higher than a pressure in the secondvalve chamber, causing the diaphragm to deform greatly and the peripheryof the hole portion in the diaphragm to separate greatly from a portionof the valve housing.

According to this configuration, the flow channel formation portion isprovided in at least a portion of the wall portion of the valve housingthat opposes the diaphragm. Accordingly, even if the periphery of thehole portion in the diaphragm makes contact with the wall portion of thevalve housing, the first opening portion and the second opening portionare able to communicate via the first valve chamber, the hole portion,the flow channel formation portion, and the second valve chamber.

As a result, the hole portion in the diaphragm will not be covered bythe wall portion of the valve housing, and a fluid is able to flow fromthe first valve chamber, through the hole portion, and into the secondvalve chamber. In other words, a flow channel for the fluid is secured.

Therefore, according to this configuration, in a valve that blocks theflow of a fluid from one main surface side of a diaphragm to anothermain surface side of the diaphragm, the transport of fluid is preventedfrom stopping even in the case where pressure on the other main surfaceside of the diaphragm has become extremely high. Furthermore, accordingto this configuration, a fluid flow channel is secured even if thedistance between the diaphragm and the wall portion of the valve housingis reduced, and thus the profile of the valve is able to be reduced aswell.

It is preferable that the diaphragm be anchored to the valve housing sothat the periphery of the hole portion in the diaphragm makes contactwith or separates from the valve housing due to a difference between apressure in the first valve chamber and a pressure in the second valvechamber.

It is preferable that the flow channel formation portion be a groove andthat the groove be configured so as to extend from a region of the wallportion that opposes the hole portion in the diaphragm to a region ofthe wall portion that opposes a portion of the diaphragm aside from thehole portion.

According to this configuration, the hole portion in the diaphragm isstill able to communicate with the second valve chamber via the grooveeven if the pressure in the first valve chamber has become much higherthan the pressure in the second valve chamber, the diaphragm hasdeformed greatly, and the diaphragm makes contact with a region of thevalve housing across a wide range as a result.

Accordingly, in this configuration as well, the hole portion in thediaphragm will not be covered, and the fluid still is able to flow fromthe first valve chamber, through the hole portion, and into the secondvalve chamber. In other words, a flow channel for the fluid is secured.Therefore, according to this configuration, the transport of fluid isfurther suppressed or prevented from stopping.

It is preferable that the flow channel formation portion be a projectionand that the projection be arranged so as to extend from a region of thewall portion that opposes the hole portion in the diaphragm to a regionof the wall portion that opposes a part of the diaphragm aside from thehole portion.

According to this configuration, the hole portion in the diaphragm isconfigured to communicate directly with the second valve chamber even ifthe pressure in the first valve chamber has become much higher than thepressure in the second valve chamber, the diaphragm has deformedgreatly, and the diaphragm makes contact with a region of the valvehousing across a wide range as a result.

Accordingly, in this configuration as well, the hole portion in thediaphragm will not be covered, and the fluid is able to flow from thefirst valve chamber, through the hole portion, and into the second valvechamber. In other words, a flow channel for the fluid is secured.Therefore, according to this configuration, the transport of fluid isfurther suppressed or prevented from stopping.

It is preferable that a width of the flow channel formation portion besmaller than a diameter of the hole portion in the diaphragm.

In the case where the width of the flow channel formation portion isgreater than the diameter of the hole portion in the diaphragm, there isa risk that the periphery of the hole portion in the diaphragm will makecontact with the flow channel formation portion and the hole portionwill be covered as a result.

However, according to this configuration, the width of the flow channelformation portion preferably is smaller than the diameter of the holeportion in the diaphragm, and thus the periphery of the hole portion inthe diaphragm is prevented from making contact with the flow channelformation portion and the hole portion is prevented from being coveredas a result. Therefore, according to this configuration, the transportof fluid is further suppressed or prevented from stopping.

It is preferable that the valve housing be provided with a projectingportion that projects toward the diaphragm in the first valve chamber,and that the periphery of the hole portion in the diaphragm make contactwith the projecting portion.

According to this configuration, the periphery of the hole portion inthe diaphragm will separate from the projecting portion and enable thefirst opening portion and the second opening portion to communicate witheach other in the case where, for example, the pressure in the firstvalve chamber is higher than the pressure in the second valve chamber.Meanwhile, the periphery of the hole portion in the diaphragm will makecontact with the projecting portion and prevent the first openingportion and the second opening portion from communicating with eachother in the case where, for example, the pressure in the first valvechamber is lower than the pressure in the second valve chamber.

It is preferable that the first valve chamber, the second valve chamber,and the projecting portion each have cylindrical or substantiallycylindrical shapes when viewed from above in a direction perpendicularto the diaphragm.

According to this configuration, the first valve chamber and the secondvalve chamber have circular or substantially circular outer shapes, andthus uniform tension acts on the diaphragm (and particularly in theperiphery near the hole portion). Accordingly, the diaphragm isprevented from making contact with the hole portion thereof tiltedrelative to the projecting portion, the hole portion in the diaphragm isprevented from shifting relative to the projecting portion in thehorizontal direction, and so on. Therefore, according to thisconfiguration, the opening/closing of the valve is carried out withcertainty.

It is preferable that the valve further include a first adhesive sheetand a second adhesive sheet, and that the valve housing include a firstvalve housing in which the first opening portion is provided and asecond valve housing in which the second opening portion is provided,the first valve housing and the diaphragm be bonded to each other by thefirst adhesive sheet and the diaphragm and the second valve housing bebonded to each other by the second adhesive sheet, a first through-holebe provided in a region of the first adhesive sheet that faces the firstvalve chamber and a second through-hole be provided in a region of thesecond adhesive sheet that faces the second valve chamber, an outercircumference of the first through-hole be greater than an outercircumference of the projecting portion and smaller than an outercircumference of the first valve chamber, and an outer circumference ofthe second through-hole be greater than the outer circumference of theprojecting portion and smaller than an outer circumference of the secondvalve chamber.

According to this configuration, a portion of the first adhesive sheetis located within the first valve chamber, and a portion of the secondadhesive sheet is located within the second valve chamber. Accordingly,the first adhesive sheet and the second adhesive sheet bond the firstand second valve housings and the diaphragm, and foreign objects presentin the respective valve chambers are caught.

Therefore, according to this configuration, even if foreign objects haveentered into the valve, for example, erroneous operations caused by suchforeign objects are prevented.

Furthermore, a fluid control apparatus according to another preferredembodiment the present invention has the following configuration.

It is preferable that the fluid control apparatus include a pumpprovided with an ejection hole and the valve according to any one of thepreferred embodiments of the present invention described above, and thatthe first opening portion of the valve be connected to the ejection holeof the pump, and the second opening portion of the valve be connected toa fluid holding portion that holds a fluid.

According to this configuration, by including the valve according to anyone of the preferred embodiments of the present invention describedabove, the fluid control apparatus that includes the valve achieves thesame effects as those described thus far.

Note that in this configuration, the pump preferably includes, forexample, an actuator in which a peripheral portion is unrestricted orsubstantially unrestricted and that bends and vibrates from a centralportion to the peripheral portion, and a planar portion disposed near toand opposing the actuator, and one or a plurality of ventilation holesare provided in an actuator-opposing region of the planar portion thatopposes the actuator. According to this configuration, a pump that iscapable of high pressures and a high flow rate while being small andhaving a low profile is used, which makes it possible to provide an evensmaller, low-profile fluid control apparatus.

According to various preferred embodiments of the present invention, ina valve that blocks the flow of a fluid from one main surface side of adiaphragm to the other main surface side of the diaphragm, the transportof fluid is prevented from stopping even in the case where pressure onthe other main surface side of the diaphragm has become extremely high.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating the primary components ofa fluid control apparatus 100 according to a first preferred embodimentof the present invention.

FIG. 2 is an exploded perspective view illustrating a piezoelectric pump10 shown in FIG. 1.

FIG. 3 is a cross-sectional view illustrating the primary components ofthe piezoelectric pump 10 shown in FIG. 1.

FIG. 4 is an exploded perspective view illustrating a valve 101 shown inFIG. 1.

FIG. 5 is an exploded perspective view illustrating the valve 101 shownin FIG. 1.

FIG. 6 is an enlarged front view illustrating the primary components ofan upper valve housing 191 shown in FIG. 5.

FIG. 7 is a schematic diagram illustrating the flow of air in the fluidcontrol apparatus 100 shown in FIG. 1 when the piezoelectric pump 10 isdriven.

FIG. 8 is a schematic diagram illustrating the flow of air in the fluidcontrol apparatus 100 shown in FIG. 1 when the piezoelectric pump 10 isdriven and an ejection pressure of the piezoelectric pump 10 has risensuddenly.

FIG. 9 is a schematic diagram illustrating the flow of air in the fluidcontrol apparatus 100 shown in FIG. 1 immediately after driving of thepiezoelectric pump 10 is stopped.

FIG. 10 is a cross-sectional view illustrating the primary components ofa fluid control apparatus 200 according to a second preferred embodimentof the present invention.

FIG. 11 is an enlarged front view illustrating the primary components ofan upper valve housing 291 shown in FIG. 10.

FIG. 12 is a schematic diagram illustrating the flow of air in the fluidcontrol apparatus 200 shown in FIG. 10 when the piezoelectric pump 10 isdriven and an ejection pressure of the piezoelectric pump 10 has risensuddenly.

FIG. 13 is a cross-sectional view illustrating the primary components ofa fluid control apparatus 300 according to a variation of the firstpreferred embodiment of the present invention.

FIG. 14 is an exploded perspective view illustrating a diaphragm pump 90according to Japanese Unexamined Patent Application Publication No.2002-106469.

FIG. 15 is a cross-sectional view illustrating the primary components ofthe diaphragm pump 90 shown in FIG. 14.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Preferred Embodiment

A fluid control apparatus 100 according to a first preferred embodimentof the present invention will be described hereinafter.

FIG. 1 is a cross-sectional view illustrating the primary components ofthe fluid control apparatus 100 according to the first preferredembodiment of the present invention.

The fluid control apparatus 100 includes a piezoelectric pump 10 and avalve 101. The valve 101 is connected to the piezoelectric pump 10 by atop surface of the piezoelectric pump 10 being bonded to a bottomsurface of the valve 101.

The valve 101 is provided with a cuff connection port 106A that enablescommunication with a manchette rubber tube 109A of a cuff 109. The fluidcontrol apparatus 100 is connected to the cuff 109 by the manchetterubber tube 109A of the cuff 109 being attached to the cuff connectionport 106A of the valve 101.

Note that the cuff 109 corresponds to a “fluid holding portion”.

The structure of the piezoelectric pump 10 and the valve 101 will now bedescribed in detail. First, the structure of the piezoelectric pump 10will be described in detail using FIGS. 2 and 3.

FIG. 2 is an exploded perspective view illustrating the piezoelectricpump 10 shown in FIG. 1, and FIG. 3 is a cross-sectional viewillustrating the primary components of the piezoelectric pump 10. Thepiezoelectric pump 10 has a structure in which a substrate 91, aflexible plate 51, a spacer 53A, a reinforcement plate 43, a vibratingplate unit 60, a piezoelectric element 42, a spacer 53B, an electrodeconducting plate 70, a spacer 53C, and a cover plate 54 are stacked inthat order.

The piezoelectric element 42 is bonded and anchored to a top surface ofa circular or substantially circular plate-shaped vibrating plate 41,the reinforcement plate 43 is affixed to a bottom surface of thevibrating plate 41, and a circular or substantially circularpiezoelectric actuator 40 is configured by the vibrating plate 41, thepiezoelectric element 42, and the reinforcement plate 43. Thepiezoelectric element 42 is configured of a PZT-based ceramic material,for example.

Here, by configuring the vibrating plate 41 of a metal plate having agreater coefficient of linear expansion than the piezoelectric element42 and the reinforcement plate 43 and bonding the vibrating plate 41through thermosetting, an appropriate amount of compressive stress canbe left in the piezoelectric element 42 without the piezoelectricactuator 40 warping as a whole, which makes it possible to prevent thepiezoelectric element 42 from breaking.

For example, it is preferable for the vibrating plate 41 to beconfigured of a material that has a high coefficient of linearexpansion, such as phosphor bronze (C5210) or stainless steel SUS301,and for the reinforcement plate 43 to be configured of 42 nickel, 36nickel, stainless steel SUS430, or the like.

Note that the vibrating plate 41, the piezoelectric element 42, and thereinforcement plate 43 may be disposed in order from the piezoelectricelement 42, to the reinforcement plate 43, and to the vibrating plate41. In this case as well, the coefficient of linear expansion isadjusted by reversing the materials of the reinforcement plate 43 andthe vibrating plate so that an appropriate compressive stress remains inthe piezoelectric element 42.

A frame plate 61 is provided in the periphery of the vibrating plate 41,and the vibrating plate 41 is connected to the frame plate 61 viaconnecting portions 62. The connecting portions 62 are provided in athin ring shape, for example, and have an elastic structure in whichelasticity is provided at a low spring constant.

Accordingly, the vibrating plate 41 is supported relative to the frameplate 61 in a flexible manner by the two connecting portions 62. Bendingvibration of the vibrating plate is almost uninhibited as a result. Inother words, a peripheral portion (and of course a central portion) ofthe piezoelectric actuator 40 is unrestricted or substantiallyunrestricted.

Note that the spacer 53A is provided in order to hold the piezoelectricactuator 40 at a set gap from the flexible plate 51. The frame plate 61is provided with an external terminal 63 to achieve an electricalconnection.

The vibrating plate 41, the frame plate 61, the connecting portions 62,and the external terminal 63 are formed preferably by carrying out astamping process on a metal plate, for example, and the vibrating plateunit 60 is configured of those elements.

The spacer 53B, which is configured of a resin, is bonded and anchoredto a top surface of the frame plate 61. The spacer 53B is as thick as orslightly thicker than the piezoelectric element 42. The frame plate 61configures a portion of a pump housing 80. The electrode conductingplate 70 described hereinafter is electrically insulated from thevibrating plate unit 60.

The electrode conducting plate 70, which is configured of a metal, isbonded and anchored to a top surface of the spacer 53B. The electrodeconducting plate 70 preferably includes a frame section 71 including acircular or substantially circular opening, an internal terminal 73 thatprojects into the opening, and an external terminal 72 that projects tothe exterior.

A leading end of the internal terminal 73 is soldered to a surface ofthe piezoelectric element 42. The internal terminal 73 is prevented fromvibrating by setting the solder location to a location corresponding toa node point of a bending vibration in the piezoelectric actuator 40.

The spacer 53C, which is configured of a resin, is bonded to andanchored upon the electrode conducting plate 70. Here, the spacer 53Cpreferably has the same or approximately the same thickness as thepiezoelectric element 42. The spacer 53C is a spacer configured toensure that the solder portion of the internal terminal 73 does not makecontact with the cover plate 54 when the piezoelectric actuator 40vibrates. The spacer 53C also prevents the surface of the piezoelectricelement 42 from coming too close to the cover plate 54 and causing adrop in the vibration amplitude due to air resistance. Accordingly, itis preferable for the thickness of the spacer 53C to the same orapproximately the same thickness as the piezoelectric element 42, asmentioned earlier.

Ejection holes 55 and 56 are provided in the cover plate 54. The coverplate 54 is placed on an upper portion of the spacer 53C and covers theperiphery of the piezoelectric actuator 40.

Meanwhile, a suction hole 52 is provided in the center of the flexibleplate 51. The spacer 53A, which adds approximately several tens of μm tothe thickness of the reinforcement plate 43, is inserted between theflexible plate 51 and the vibrating plate unit 60. Accordingly, thevibrating plate 41 is not restricted by the frame plate 61 even if thespacer 53A is present, and thus the interval changes automatically inaccordance with load fluctuations.

However, the vibrating plate 41 is slightly susceptible to restrictionsfrom the connecting portions 62 (spring terminals), and thus insertingthe spacer 53A in this manner makes it possible to purposefully secure agap and increase the flow rate at times of low load. Furthermore, evenin the case where the spacer 53A is inserted, the connecting portions 62(spring terminals) bend and the gap between opposing regions of thepiezoelectric actuator 40 and the flexible plate automatically shrinksat times of high load, which makes operations at high pressurespossible.

Although the connecting portions 62 are provided in two locations in theexample shown in FIG. 2, the connecting portions 62 may be provided inthree or more locations. Although the connecting portions 62 do notinterfere with the vibration of the piezoelectric actuator 40, theconnecting portions 62 do slightly affect the vibration, and thusconnecting (holding) the piezoelectric actuator 40 in three locations,for example, makes it possible to hold the actuator in a more naturalmanner and prevent the piezoelectric element 42 from breaking.

The substrate 91, in the center of which is provided a cylindrical orsubstantially cylindrical opening portion 92, is provided below theflexible plate 51. A portion of the flexible plate 51 is exposed by theopening portion 92 of the substrate 91. This circular or substantiallycircular exposed portion vibrates at substantially the same frequency asthe piezoelectric actuator 40, due to pressure fluctuations producedwhen the piezoelectric actuator 40 vibrates.

The configuration of the flexible plate 51 and the substrate 91 producesa mobile portion that can bend and vibrate in the center or near thecenter of the region of the flexible plate 51 that opposes thepiezoelectric actuator, and the peripheral portion then defines andserves as a fixed portion that is restricted or substantiallyrestricted. A natural vibration frequency of this circular orsubstantially circular mobile portion is designed to be the same as orslightly lower than a driving frequency of the piezoelectric actuator40.

Accordingly, when a driving voltage is applied to the external terminals63 and 72, the piezoelectric actuator 40 bends and vibrates in aconcentric circle shape, and the exposed portion of the flexible plate51 centered on the suction hole 52 also vibrates at a high amplitude inresponse to the piezoelectric actuator 40 vibrating.

When a vibration phase of the flexible plate 51 is delayed relative to avibration phase of the piezoelectric actuator 40 (by about 90°, forexample), fluctuations in the thickness of the gap space between theflexible plate 51 and the piezoelectric actuator 40 substantiallyincrease. The capabilities of the pump are further improved as a result.

Next, the structure of the valve 101 will be described in detail withreference to FIGS. 1 and 4-6.

FIGS. 4 and 5 are exploded perspective views illustrating the valve 101shown in FIG. 1. FIG. 4 is an exploded perspective view of the valve 101seen from the top surface side that is connected to the cuff 109, andFIG. 5 is an exploded perspective view of the valve 101 seen from thebottom surface side that is bonded to the piezoelectric pump 10. FIG. 6is an enlarged front view illustrating the primary components of theupper valve housing 191 shown in FIG. 5.

Note that a “first opening portion” corresponds to a first ventilationhole 111. A “second opening portion” corresponds to a second ventilationhole 112. Furthermore, a “first valve chamber” corresponds to a firstlower valve chamber 131. A “second valve chamber” corresponds to a firstupper valve chamber 133.

As shown in FIGS. 1, 4, and 5, the valve 101 has a structure in which alower valve housing 192, a first adhesive sheet 151 configured of arectangular or substantially rectangular thin film, a diaphragm 120configured of a rectangular or substantially rectangular thin film, asecond adhesive sheet 152 configured of a rectangular or substantiallyrectangular thin film, and the upper valve housing 191 are stacked inthat order. The upper valve housing 191 and the lower valve housing 192configure a valve housing 130.

The lower valve housing 192 and the diaphragm 120 are bonded to eachother by the first adhesive sheet 151, and the diaphragm 120 and theupper valve housing 191 are bonded to each other by the second adhesivesheet 152.

As shown in FIG. 1, the top surface of the piezoelectric pump 10 isbonded to a bottom surface of the lower valve housing 192. As shown inFIGS. 1, 4, and 5, a fourth ventilation hole 110 that communicates withthe ejection hole 56 of the piezoelectric pump 10, the first ventilationhole 111 that communicates with the ejection hole 55 of thepiezoelectric pump 10, and a cylindrical projecting portion 138 thatprojects toward the diaphragm 120 side are provided in the lower valvehousing 192.

As shown in FIGS. 1, 4, and 5, the second ventilation hole 112 thatcommunicates with the cuff 109, a third ventilation hole 113 thatcommunicates with the exterior of the fluid control apparatus 100, and avalve seat 139 that projects toward the diaphragm 120 side from theperiphery of the third ventilation hole 113 are provided in the uppervalve housing 191. The valve seat 139 has a cylindrical or substantiallycylindrical shape in a central area of which the third ventilation hole113 is provided.

As shown in FIGS. 1, 4, and 5, a circular or substantially circular holeportion 121 is provided in a central portion of a region of thediaphragm 120 that opposes the projecting portion 138. The diameter ofthe hole portion 121 is set to be smaller than the diameter of a face ofthe projecting portion 138 that makes contact with the diaphragm 120.

The diaphragm 120 is sandwiched from both sides between the upper valvehousing 191 and the lower valve housing 192, and is bonded to the uppervalve housing 191 and the lower valve housing 192 so as to make contactwith the valve seat 139 and so that the periphery of the hole portion121 makes contact with the projecting portion 138.

The diaphragm 120 divides the interior of the valve housing 130 as aresult. The ring-shaped first lower valve chamber 131 that communicateswith the first ventilation hole 111, a cylindrical or substantiallycylindrical second lower valve chamber 132 that communicates with thefourth ventilation hole 110, the cylindrical or substantiallycylindrical first upper valve chamber 133 that communicates with thesecond ventilation hole 112 via a communication channel 135, and aring-shaped second upper valve chamber 134 that communicates with thefirst upper valve chamber 133 via the communication channel 135 areconfigured as well. The shapes of the valve chambers mentioned here areshapes as viewed from above, in a direction perpendicular orsubstantially perpendicular to the diaphragm 120.

The diameters of the first lower valve chamber 131, the second lowervalve chamber 132, the first upper valve chamber 133, and the secondupper valve chamber 134 are each preferably about 7.0 mm, for example.The diameter of the face of the projecting portion 138 that makescontact with the diaphragm 120 is preferably about 1.5 mm, for example.

First through-holes 155A-155C are provided in a region of the firstadhesive sheet 151 that faces the first lower valve chamber 131 and thesecond lower valve chamber 132. The first through-hole 155A has acircular or substantially circular shape that has approximately the samecenter axis as the first lower valve chamber 131, for example. The firstthrough-hole 155B has a circular or substantially circular shape thathas approximately the same center axis as the second lower valve chamber132, for example. The first through-holes 155A and 155B preferably eachhave a diameter of about 6.6 mm, for example.

Accordingly, the diameter of the first through-hole 155A is greater thanthe diameter of the projecting portion 138 and smaller than the diameterof the first lower valve chamber 131. In other words, an outercircumference of the first through-hole 155A is greater than an outercircumference of the projecting portion 138 and smaller than an outercircumference of the first lower valve chamber 131.

Likewise, the diameter of the first through-hole 155B is smaller thanthe diameter of the second lower valve chamber 132. In other words, theouter circumference of the first through-hole 155B is smaller than theouter circumference of the second lower valve chamber 132.

Second through-holes 156A-156C are provided in a region of the secondadhesive sheet 152 that faces the first upper valve chamber 133, thecommunication channel 135, and the second upper valve chamber 134. Thesecond through-hole 156A has a circular or substantially circular shapethat has approximately the same center axis as the first upper valvechamber 133, for example. The second through-hole 156B has a circular orsubstantially circular shape that has approximately the same center axisas the second upper valve chamber 134, for example. The secondthrough-holes 156A and 156B each have a diameter preferably of about 6.6mm, for example.

Accordingly, the diameter of the second through-hole 156A is smallerthan the diameter of the first upper valve chamber 133. In other words,the outer circumference of the second through-hole 156A is smaller thanthe outer circumference of the first upper valve chamber 133.

Likewise, the diameter of the second through-hole 156B is smaller thanthe diameter of the second upper valve chamber 134. In other words, theouter circumference of the second through-hole 156B is smaller than theouter circumference of the second upper valve chamber 134.

As described thus far, according to the valve 101, a portion of thefirst adhesive sheet 151 is located within the first lower valve chamber131 and the second lower valve chamber 132. Likewise, a portion of thesecond adhesive sheet 152 is located within the first upper valvechamber 133 and the second upper valve chamber 134.

Meanwhile, as shown in FIG. 6, the upper valve housing 191 includes, inthe first upper valve chamber 133, a wall portion 190 that opposes thediaphragm 120. The wall portion 190 includes a region 191A that opposesan area of the diaphragm 120 aside from the hole portion 121 and aregion 191B that opposes the hole portion 121 in the diaphragm 120.

A groove 140 is provided in the wall portion 190 of the upper valvehousing 191 that opposes the diaphragm 120 in the first upper valvechamber 133. The groove 140 is a groove that allows the first lowervalve chamber 131 and the first upper valve chamber 133 to communicatevia the hole portion 121 when the diaphragm 120 makes contact with thewall portion 190. Note that the groove 140 corresponds to a “flowchannel formation portion”.

A width X of the groove 140 is, as shown in FIG. 6, shorter than adiameter R of the region 191B of the upper valve housing 191 thatopposes the hole portion 121 of the diaphragm 120 in the first uppervalve chamber 133. Meanwhile, as shown in FIGS. 1, 5, and 6, the groove140 is arranged to encompass a range from the region 191B to the secondventilation hole 112 of the upper valve housing 191. The groove 140 isarranged so as to extend from the region 191B to the region 191A of theupper valve housing 191.

The projecting portion 138 is arranged in the lower valve housing 192 soas to pressurize the periphery of the hole portion 121 in the diaphragm120.

Accordingly, the valve 101 includes a check valve 102 and an exhaustvalve 103, as shown in FIG. 1.

First, the check valve 102 is configured by a portion of the lower valvehousing 192 that includes the first ventilation hole 111, a portion ofthe upper valve housing 191 that includes the second ventilation hole112, the periphery of the hole portion 121 in the diaphragm 120, and theprojecting portion 138 that makes contact with that periphery and coversthe hole portion 121. The check valve 102 allows the fluid to flow fromthe first lower valve chamber 131 side toward the first upper valvechamber 133 side and blocks the fluid from flowing from the first uppervalve chamber 133 side toward the first lower valve chamber 131 side.

As a result of a pressure difference between the first lower valvechamber 131 and the first upper valve chamber 133, the check valve 102causes the diaphragm 120 to come into contact with or separate from theprojecting portion 138.

Next, the exhaust valve 103 is configured by a portion of the lowervalve housing 192 that includes the fourth ventilation hole 110, aportion of the upper valve housing 191 that includes the secondventilation hole 112 and the third ventilation hole 113, a portion ofthe diaphragm 120, and the valve seat 139 that projects toward thediaphragm 120 side from the periphery of the third ventilation hole 113,makes contact with the diaphragm 120, and is covered thereby.

As a result of a pressure difference between the second lower valvechamber 132 and the second upper valve chamber 134, the exhaust valve103 causes the diaphragm 120 to come into contact with or separate fromthe valve seat 139.

Next, operations of the fluid control apparatus 100 during bloodpressure measurement will be described.

FIG. 7 is a schematic diagram illustrating the flow of air in the fluidcontrol apparatus 100 shown in FIG. 1 when the piezoelectric pump 10 isdriven.

When blood pressure measurement begins, first, the fluid controlapparatus 100 drives the piezoelectric pump 10. When the piezoelectricpump 10 is driven, first, air flows from the opening portion 92 and thesuction hole 52 into a pump chamber 45 within the piezoelectric pump 10.Next, the air is ejected from the ejection holes 55 and 56, and flowsinto both the second lower valve chamber 132 and the first lower valvechamber 131 of the valve 101.

As a result, in the exhaust valve 103, a pressure in the second lowervalve chamber 132 becomes higher than a pressure in the second uppervalve chamber 134. Accordingly, as shown in FIG. 8, the diaphragm 120seals the third ventilation hole 113 and blocks the passage of airbetween the second ventilation hole 112 and the third ventilation hole113.

Meanwhile, in the check valve 102, a pressure in the first lower valvechamber 131 becomes higher than a pressure in the first upper valvechamber 133. Accordingly, the periphery of the hole portion 121 in thediaphragm 120 separates from the projecting portion 138, and the firstventilation hole 111 and the second ventilation hole 112 communicate viathe hole portion 121.

As a result, the air is discharged from the piezoelectric pump 10,through the first ventilation hole 111, the hole portion 121, and thesecond ventilation hole 112 of the valve 101, and to the cuff 109 (seeFIG. 7), and the pressure (air pressure) within the cuff 109 increases.

Note that the diaphragm 120 is anchored to the valve housing 130 so thatthe periphery of the hole portion 121 in the diaphragm 120 makes contactwith the projecting portion 138. The projecting portion 138 pressurizesthe periphery of the hole portion 121 in the diaphragm 120.

Accordingly, the air that flows out from the hole portion 121 via thefirst ventilation hole 111 in the valve 101 takes on a slightly lowerpressure than the ejection pressure of the piezoelectric pump 10, andflows into the first upper valve chamber 133 and the second upper valvechamber 134 from the hole portion 121. On the other hand, the ejectionpressure of the piezoelectric pump 10 acts on the second lower valvechamber 132.

As a result, in the valve 101, the pressure in the second lower valvechamber 132 slightly exceeds the pressure in the second upper valvechamber 134, the diaphragm 120 seals the third ventilation hole 113, andthe hole portion 121 remains in an open state.

FIG. 8 is a schematic diagram illustrating the flow of air in the fluidcontrol apparatus 100 when the piezoelectric pump 10 shown in FIG. 7 isdriven and the ejection pressure of the piezoelectric pump 10 has risensuddenly.

Here, when the pressure in the first lower valve chamber 131 suddenlyrises, the diaphragm 120 deforms greatly, and there are cases where theperiphery of the hole portion 121 in the diaphragm 120 separates greatlyfrom the projecting portion 138, as shown in FIG. 8.

In this case, according to this configuration, the diaphragm 120 makescontact with the region 191A of the upper valve housing 191 (see FIG.6), but the hole portion 121 in the diaphragm 120 communicates with thefirst upper valve chamber 133 via the groove 140.

Accordingly, with the check valve 102 provided with the groove 140, evenif, the pressure in the first lower valve chamber 131 has risensuddenly, the hole portion 121 in the diaphragm 120 will not be covered,and the air will flow from the first lower valve chamber 131 into thefirst upper valve chamber 133 via the hole portion 121. In other words,a flow channel for the air is secured.

Therefore, according to the check valve 102, the transport of air isprevented from being stopped even in the case where the ejectionpressure of the piezoelectric pump 10 has risen suddenly.

Furthermore, in the check valve 102, the width X of the groove 140 isshorter than the diameter R of the hole portion 121 in the diaphragm 120(see FIG. 6). Therefore, according to the check valve 102, the peripheryof the hole portion 121 in the diaphragm 120 is prevented from makingcontact with the groove 140, which in turn prevents the hole portion 121from being covered. Accordingly, the transport of air is furthersuppressed or prevented from stopping.

Meanwhile, in the upper valve housing 191 of the check valve 102, thegroove 140 is provided in a range spanning from the region 191B thatopposes the hole portion 121 in the diaphragm 120 to the secondventilation hole 112 (see FIG. 6).

Accordingly, even if the pressure in the first lower valve chamber 131becomes much higher than the pressure in the first upper valve chamber133 and the diaphragm 120 makes contact with a wide range of the uppervalve housing 191 as a result, the hole portion 121 in the diaphragm 120communicates with the first upper valve chamber 133 via the groove 140.

As a result, the hole portion 121 in the diaphragm 120 will not becovered, and the air will flow from the first lower valve chamber 131into the first upper valve chamber 133 through the hole portion 121. Inother words, a flow channel for the air is secured. Accordingly, thetransport of air is further suppressed or prevented from stopping.

Furthermore, according to this configuration, an air flow channel issecured even if the distance between the diaphragm 120 and the wallportion 190 of the upper valve housing 191 is significantly reduced, andthus the profile of the check valve 102 is significantly reduced aswell.

Further still, as shown in FIGS. 4 and 5, in the valve 101, the valvechambers 131, 132, 133, and 134 each have circular or substantiallycircular outer shapes, and thus uniform tension acts on the diaphragm120 (and particularly in the periphery near the hole portion 121).

Accordingly, the diaphragm 120 is suppressed or prevented from makingcontact with the hole portion 121 thereof tilted relative to theprojecting portion 138, the hole portion 121 in the diaphragm 120 issuppressed from shifting relative to the projecting portion 138 in thehorizontal direction, and so on. Therefore, according to the valve 101,the opening/closing of the respective valves is carried out with morecertainty.

FIG. 9 is a schematic diagram illustrating the flow of air in the fluidcontrol apparatus 100 shown in FIG. 1 immediately after the driving ofthe piezoelectric pump 10 has stopped.

When the blood pressure measurement ends, the fluid control apparatus100 stops driving the piezoelectric pump 10. Here, when the driving ofthe piezoelectric pump 10 stops, the air in the pump chamber 45, thefirst lower valve chamber 131, and the second lower valve chamber 132 isquickly exhausted to the exterior of the fluid control apparatus 100from the suction hole 52 and the opening portion 92 in the piezoelectricpump 10. Meanwhile, pressure from the cuff 109 acts on the first uppervalve chamber 133 and the second upper valve chamber 134 from the secondventilation hole 112.

As a result, in the check valve 102, the pressure in the first lowervalve chamber 131 becomes lower than the pressure in the first uppervalve chamber 133. The diaphragm 120 makes contact with the projectingportion 138 and seals the hole portion 121.

Meanwhile, in the exhaust valve 103, the pressure in the second lowervalve chamber 132 becomes lower than the pressure in the second uppervalve chamber 134. The diaphragm 120 separates from the valve seat 139and opens the third ventilation hole 113.

In other words, in the valve 101, the second ventilation hole 112 andthe third ventilation hole 113 communicate via the communication channel135 and the second upper valve chamber 134. Through this, the air in thecuff 109 is quickly exhausted from the third ventilation hole 113 viathe second ventilation hole 112, the communication channel 135, and thesecond upper valve chamber 134 (see FIG. 9).

Therefore, according to the valve 101 in this preferred embodiment, airis quickly exhausted from the cuff 109 after the cuff 109 has beenfilled with compressed air.

Meanwhile, in the valve 101, part of the first adhesive sheet 151 islocated within the first lower valve chamber 131 and the second lowervalve chamber 132, and a portion of the second adhesive sheet 152 islocated within the first upper valve chamber 133 and the second uppervalve chamber 134, as described earlier.

Accordingly, the first adhesive sheet 151 and the second adhesive sheet152 bond the valve housing 130 and the diaphragm 120, and foreignobjects present in the valve chambers 131, 132, 133, and 134 are caught.

Therefore, according to the valve 101, even if foreign objects haveentered into the valve 101, for example, erroneous operations caused bysuch foreign objects are suppressed or prevented. In particular, thethird ventilation hole 113 of the valve seat 139 in the exhaust valve103 is suppressed or prevented from being blocked by foreign objects.

The fluid control apparatus 100 that includes the valve 101 according tothis preferred embodiment achieves the same effects as those describedthus far.

Second Preferred Embodiment

A fluid control apparatus 200 according to a second preferred embodimentof the present invention will be described hereinafter.

FIG. 10 is a cross-sectional view illustrating the primary components ofthe fluid control apparatus 200 according to the second preferredembodiment of the present invention. FIG. 11 is an enlarged front viewillustrating the primary components of an upper valve housing 291 shownin FIG. 10. FIG. 12 is a schematic diagram illustrating the flow of airin the fluid control apparatus 200 when the piezoelectric pump 10 isdriven and the ejection pressure of the piezoelectric pump 10 has risensuddenly while the fluid control apparatus 200 shown in FIG. 10 isoperating.

The fluid control apparatus 200 differs from the fluid control apparatus100 in that the upper valve housing 291 of a valve 201 includes aprojection 240 instead of the groove 140. Note that the projection 240corresponds to a “flow channel formation portion”. The other elements ofthe configuration are the same.

To describe in detail, the upper valve housing 291 includes, in thefirst upper valve chamber 133, a wall portion 290 that opposes thediaphragm 120. The wall portion 290 includes a region 291A that opposesan area of the diaphragm 120 aside from the hole portion 121 and aregion 291B that opposes the hole portion 121 in the diaphragm 120.

To describe in further detail, the projection 240 is provided in thewall portion 290 of the upper valve housing 291 that opposes thediaphragm 120 in the first upper valve chamber 133. The projection 240is a projection that allows the first lower valve chamber 131 and thefirst upper valve chamber 133 to communicate via the hole portion 121when the diaphragm 120 makes contact with the wall portion 290 of theupper valve housing 291.

A width X of the projection 240 is, as shown in FIG. 11, shorter than adiameter R of the region 291B of the upper valve housing 291 thatopposes the hole portion 121 of the diaphragm 120 in the first uppervalve chamber 133. The projection 240 is arranged so as to extend fromthe region 291B to the region 291A of the upper valve housing 291.

In the valve 201 according to this preferred embodiment as well, whenthe pressure in the first lower valve chamber 131 suddenly rises, thediaphragm 120 deforms greatly, and there are cases where the peripheryof the hole portion 121 in the diaphragm 120 separates by a significantamount from the projecting portion 138, as shown in FIG. 12.

In such a case, with the valve 201, the diaphragm 120 makes contact withthe projection 240, a gap is defined between the diaphragm 120 and theregion 291A of the upper valve housing 291, and the hole portion 121 inthe diaphragm 120 communicates with the first upper valve chamber 133.

Accordingly, with the valve 201 provided with the projection 240, evenif, the pressure in the first lower valve chamber 131 has risensuddenly, the hole portion 121 in the diaphragm 120 will not be covered,and the air will flow from the first lower valve chamber 131 into thefirst upper valve chamber 133 via the hole portion 121. In other words,a flow channel for the air is secured.

Accordingly, the valve 201 and the fluid control apparatus 200 providethe same effects as those of the valve 101 and the fluid controlapparatus 100 according to the first preferred embodiment.

Other Preferred Embodiments

Although the aforementioned preferred embodiments describe air as afluid, it should be noted that the fluid is not limited thereto, andpreferred embodiments of the present invention are applicable even whenthe fluid is a gas aside from air, a liquid, or the like.

In addition, although the aforementioned preferred embodiments describeproviding a unimorph actuator that preferably bends and vibrates, abimorph configuration in which piezoelectric elements are affixed toboth sides of a vibrating plate and the plate bends and vibrates as aresult may be used.

In addition, although the pump in the aforementioned preferredembodiments includes the actuator 40 that preferably bends and vibratesas a result of the piezoelectric element 42 extending and contracting,the present invention is not limited thereto. For example, an actuatorthat bends and vibrates through electromagnetic driving may be usedinstead.

In addition, although the aforementioned preferred embodiments describethe piezoelectric element as being configured preferably of a PZT-basedceramic material, the present invention is not limited thereto. Thepiezoelectric element may be configured of a non-leaded piezoelectricceramic material such as a potassium sodium niobate-based ceramicmaterial, an alkali niobate-based ceramic material, or the like.

In addition, although the aforementioned preferred embodiments describethe groove 140 or the projection 240 as preferably having an elongated,narrow shape as indicated in FIG. 6 or FIG. 11, the present invention isnot limited thereto. The groove 140 or the projection 240 may have across shape, a polygon shape, an oval shape, or the like, for example.

In addition, although the aforementioned preferred embodiments describethere preferably being only a single groove 140 or projection 240, thepresent invention is not limited thereto. For example, a plurality ofgrooves 140 may be provided in the region 191A of the upper valvehousing 191 shown in FIG. 6, and a plurality of projections 240 may beprovided in the region 291A of the upper valve housing 291 shown in FIG.11.

In addition, although the valves 101 and 201 in the aforementionedpreferred embodiments (see FIGS. 1 and 10) are described as preferablyhaving the first adhesive sheet 151 in which the outer circumference ofthe first through-hole 155A is smaller than the outer circumference ofthe first lower valve chamber 131 and the outer circumference of thefirst through-hole 155B is smaller than the outer circumference of thesecond lower valve chamber 132, the present invention is not limitedthereto. For example, a valve 301, shown in FIG. 13, may have a firstadhesive sheet 351, in which the outer circumference of the firstthrough-hole 155A is equal to the outer circumference of the first lowervalve chamber 131 and the outer circumference of the first through-hole155B is equal to the outer circumference of the second lower valvechamber 132.

Likewise, although the valves 101 and 201 in the aforementionedpreferred embodiments (see FIGS. 1 and 10) are described as preferablyhaving the second adhesive sheet 152 in which the outer circumference ofthe second through-hole 156A is smaller than the outer circumference ofthe first upper valve chamber 133 and the outer circumference of thesecond through-hole 156B is smaller than the outer circumference of thesecond upper valve chamber 134, the present invention is not limitedthereto. For example, the valve 301, shown in FIG. 13, may have a secondadhesive sheet 352, in which the outer circumference of the secondthrough-hole 156A is equal to the outer circumference of the first uppervalve chamber 133 and the outer circumference of the second through-hole156B is equal to the outer circumference of the second upper valvechamber 134.

Finally, the aforementioned preferred embodiments are to be understoodin all ways as exemplary and in no ways limiting. The scope of thepresent invention is defined not by the above preferred embodiments butby the scope of the appended claims. Furthermore, the scope of thepresent invention is intended to include all modifications within thescope and meaning equivalent to the scope of the appended claims.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A valve comprising: a valve housing including a first opening portion and a second opening portion; and a diaphragm including a hole portion and configured to define in the valve housing a first valve chamber configured to communicate with the first opening portion and a second valve chamber configured to communicate with the second opening portion; wherein a portion of the diaphragm surrounding the hole portion is in contact with a portion of the valve housing such that the portion of the valve housing covers the hole portion; and a flow channel formation portion extends from a region of a wall portion of the second valve chamber that opposes the hole portion to the second opening portion, the flow channel formation portion defining a flow channel connecting the first valve chamber and the second valve chamber.
 2. The valve according to claim 1, wherein the diaphragm is anchored to the valve housing so that the portion of the diaphragm surrounding the hole portion makes contact with or separates from the valve housing due to a difference between a pressure in the first valve chamber and a pressure in the second valve chamber.
 3. The valve according to claim 2, wherein the flow channel formation portion includes a groove; and the groove extends from the region of the wall portion that opposes the hole portion in the diaphragm to a region of the wall portion that opposes a portion of the diaphragm spaced away from the hole portion.
 4. The valve according to claim 1, wherein the flow channel formation portion includes a projection; and the projection extends from the region of the wall portion that opposes the hole portion in the diaphragm to a region of the wall portion that opposes a portion of the diaphragm spaced away from the hole portion.
 5. The valve according to claim 1, wherein a width of the flow channel formation portion is smaller than a diameter of the hole portion.
 6. The valve according to claim 1, wherein the valve housing is provided with a projecting portion that projects toward the diaphragm side in the first valve chamber; and the portion of the diaphragm surrounding the hole portion makes contact with the projecting portion.
 7. The valve according to claim 6, wherein the first valve chamber, the second valve chamber, and the projecting portion each have cylindrical or substantially cylindrical shapes when viewed from above in a direction perpendicular or substantially perpendicular to the diaphragm.
 8. The valve according to claim 7, further comprising: a first adhesive sheet; and a second adhesive sheet; wherein the valve housing includes a first valve housing in which the first opening portion is provided and a second valve housing in which the second opening portion is provided; the first valve housing and the diaphragm are bonded to each other by the first adhesive sheet and the diaphragm and the second valve housing are bonded to each other by the second adhesive sheet; a first through-hole is provided in a region of the first adhesive sheet that faces the first valve chamber and a second through-hole is provided in a region of the second adhesive sheet that faces the second valve chamber; an outer circumference of the first through-hole is greater than an outer circumference of the projecting portion and smaller than an outer circumference of the first valve chamber; and an outer circumference of the second through-hole is greater than the outer circumference of the projecting portion and smaller than an outer circumference of the second valve chamber.
 9. The valve according to claim 7, further comprising: a first adhesive sheet; and a second adhesive sheet; wherein the valve housing includes a first valve housing in which the first opening portion is provided and a second valve housing in which the second opening portion is provided; the first valve housing and the diaphragm are bonded to each other by the first adhesive sheet and the diaphragm and the second valve housing are bonded to each other by the second adhesive sheet; a first through-hole is provided in a region of the first adhesive sheet that faces the first valve chamber and a second through-hole is provided in a region of the second adhesive sheet that faces the second valve chamber; an outer circumference of the first through-hole is greater than an outer circumference of the projecting portion and equal to an outer circumference of the first valve chamber; and an outer circumference of the second through-hole is greater than the outer circumference of the projecting portion and equal to an outer circumference of the second valve chamber.
 10. The valve according to claim 1, wherein the flow channel formation portion has a shape that is one of an elongated, narrowed shape, a cross shape, a polygon shape, and an oval shape.
 11. The valve according to claim 1, wherein the flow channel formation portion includes a projection or a groove.
 12. A fluid control apparatus comprising: a pump provided with an ejection hole; and the valve according to claim 1; wherein the first opening portion of the valve is connected to the ejection hole of the pump; and the second opening portion of the valve is connected to a fluid holding portion that holds a fluid.
 13. The fluid control apparatus according to claim 12, wherein the fluid is one of a gas and a liquid.
 14. The fluid control apparatus according to claim 12, wherein the diaphragm is anchored to the valve housing so that the portion of the diaphragm surrounding the hole portion makes contact with or separates from the valve housing due to a difference between a pressure in the first valve chamber and a pressure in the second valve chamber.
 15. The fluid control apparatus according to claim 12, wherein the flow channel formation portion includes a groove; and the groove extends from the region of the wall portion that opposes the hole portion in the diaphragm to a region of the wall portion that opposes a portion of the diaphragm spaced away from the hole portion.
 16. The fluid control apparatus according to claim 12, wherein the flow channel formation portion includes a projection; and the projection extends from the region of the wall portion that opposes the hole portion in the diaphragm to a region of the wall portion that opposes a portion of the diaphragm spaced away from the hole portion.
 17. The fluid control apparatus according to claim 12, wherein a width of the flow channel formation portion is smaller than a diameter of the hole portion.
 18. The fluid control apparatus according to claim 12, wherein the valve housing is provided with a projecting portion that projects toward the diaphragm side in the first valve chamber; and the portion of the diaphragm surrounding the hole portion makes contact with the projecting portion.
 19. The fluid control apparatus according to claim 18, wherein the first valve chamber, the second valve chamber, and the projecting portion each have cylindrical or substantially cylindrical shapes when viewed from above in a direction perpendicular or substantially perpendicular to the diaphragm.
 20. The fluid control apparatus according to claim 18, further comprising: a first adhesive sheet; and a second adhesive sheet; wherein the valve housing includes a first valve housing in which the first opening portion is provided and a second valve housing in which the second opening portion is provided; the first valve housing and the diaphragm are bonded to each other by the first adhesive sheet and the diaphragm and the second valve housing are bonded to each other by the second adhesive sheet; a first through-hole is provided in a region of the first adhesive sheet that faces the first valve chamber and a second through-hole is provided in a region of the second adhesive sheet that faces the second valve chamber; an outer circumference of the first through-hole is greater than an outer circumference of the projecting portion and smaller than an outer circumference of the first valve chamber; and an outer circumference of the second through-hole is greater than the outer circumference of the projecting portion and smaller than an outer circumference of the second valve chamber. 